1. Field of the Invention
The present invention relates to an automotive headlamp apparatus, and in particular, to an automotive headlamp apparatus used in an automobile, etc.
2. Description of the Related Art
An automotive headlamp apparatus can generally switch low beam and high beam to each other. The low beam illuminates a near distance with a predetermined illuminance so as not to provide glare to forward vehicles including oncoming vehicles and leading vehicles, and is used mainly when driving in an urban area. On the other hand, the high beam illuminates a forward wide area and a remote distance with a relatively high illuminance, and is used mainly when driving at high speed on a road on which forward vehicles are few.
Although the high beam is excellent in the visibility by a driver in comparison with the low beam, there is the problem of providing glare to the drivers of other vehicles. Accordingly, when driving, in particular, in an urban area at night, there are many cases where the low beam is used. When using the low beam, a light source for the high beam is not used. On the other hand, there is always the demand that the visibility of roads by a driver should be enhanced when using the low beam.
In response to the demand, Japanese Patent Application Publication NO. 2008-37240 discloses a technique in which a plurality of high beam units for individually emitting light toward each of high beam emitting areas, which are divided into multiple areas, are provided, and when an object to which emission of light is prohibited (hereinafter, referred to as an “emission-prohibited object”) has been detected, the high beam unit that emits light to the light emitting area where an emission-prohibited object is present is turned off. According to the technique, emission of high beam toward an emission-prohibited object can be suppressed while ensuring distant visibility with high beam.
In the aforementioned situations, the present inventor has recognized the following problem. That is, when the aforementioned emission-prohibited object is an oncoming vehicle, there is the possibility that the oncoming vehicle may be turning on a headlamp. When the headlamp of an oncoming vehicle is being turned on, there is the possibility that the light emitted therefrom may be scattered within driver's eyeballs, thereby causing a threshold value for the luminance contrast to be large, that is, a luminance difference necessary for distinguishing an object to be sighted from the background to be large. As a result, there is the possibility that an effect of enhancing the visibility of a driver, obtained by emitting light toward the area where an emission-prohibited object is not present, may be suppressed.